If you go out and buy a new PS4 today, chances are the model number written on it will be some variation of CUH-2100. But that will change shortly as Sony just rolled out a CUH-2200 model.
PlayStation model number changes are made for different reasons, and the digit that changes signals the importance of the change. Major hardware revisions result in the first digit changing, which is why when the PS4 SlimBest Price at Amazon was rolled out Sony moved from model CUH-1XXX to CUH-2XXX. The last two digits vary based on which region of the world a console is intended for.
When the second digit in the model number changes it signals minor hardware tweaks, which is what this looks to be. CUH-2200 models have appeared listed on the Japanese online store with a 1TB Jet Black and 500GB Jet Black version both carrying the new model number. Eventually all markets will offer the CUH-2200 as Sony ships out new stock and stops making the CUH-2100 (this may have already happened).
These new consoles are unchanged in terms of power use, weight, and dimensions, which suggests that Sony has tweaked the hardware inside for some reason. Typically this is done when they figure out a way to save money and reduce manufacturing costs. Any saving, however small, can make a huge difference when you’re producing tens of millions of consoles every year.
It isn’t likely Sony will mention the move to model CUH-2200 as there’s no reason for it to be talked about publiclyand for most purchasers of newwaiting for the new model to role out isn’t worth it either.